Derivatives (Details) In Millions, unless otherwise specified	3 Months Ended		3 Months Ended									3 Months Ended
	Mar. 31, 2012 USD ($)	Mar. 31, 2012 Fair Value Hedging [Member] USD ($)	Mar. 31, 2012 Alabama Power [Member] USD ($)	Mar. 31, 2012 Georgia Power [Member] USD ($)	Mar. 31, 2012 Gulf Power [Member] USD ($)	Mar. 31, 2012 Mississippi Power [Member] USD ($)	Mar. 31, 2012 Mississippi Power [Member] EUR (€)	Mar. 31, 2012 Mississippi Power [Member] Derivatives not designated as hedges [Member] USD ($)	Mar. 31, 2012 Mississippi Power [Member] Derivatives not designated as hedges [Member] EUR (€)	Mar. 31, 2012 Mississippi Power [Member] Fair Value Hedging [Member] USD ($)	Mar. 31, 2012 Mississippi Power [Member] Fair Value Hedging [Member] EUR (€)	Mar. 31, 2012 Southern Power [Member] USD ($)	Mar. 31, 2012 Power [Member] MWh	Mar. 31, 2012 Power [Member] Alabama Power [Member]	Mar. 31, 2012 Power [Member] Georgia Power [Member]	Mar. 31, 2012 Power [Member] Gulf Power [Member]	Mar. 31, 2012 Power [Member] Mississippi Power [Member]	Mar. 31, 2012 Power [Member] Southern Power [Member] MWh	Mar. 31, 2012 Gas [Member] MMBTU	Mar. 31, 2012 Gas [Member] Alabama Power [Member] MMBTU	Mar. 31, 2012 Gas [Member] Georgia Power [Member] MMBTU	Mar. 31, 2012 Gas [Member] Gulf Power [Member] MMBTU	Mar. 31, 2012 Gas [Member] Mississippi Power [Member] MMBTU	Mar. 31, 2012 Gas [Member] Southern Power [Member] MMBTU	Mar. 31, 2012 Hedge Maturity Date December 2022 [Member] Alabama Power [Member] USD ($)	Mar. 31, 2012 Hedge Maturity Date December 2022 [Member] Alabama Power [Member] Cash Flow Hedging [Member] USD ($)
Energy-related derivative contracts
Net Purchased MWHs													(100,000)					(100,000)
Net Purchased mmBtu																			221,000,000	37,000,000	85,000,000	43,000,000	28,000,000	28,000,000
Longest Hedge Date																			2017	2017	2017	2017	2017	2012
Longest Non-Hedge Date													2012					2012	2017					2017
Notional amount of interest rate derivatives
Notional Amount																									$ 300
Notional Amount, Fair Value	350
Notional Amount of interest rate derivatives, Total	650
Interest Rate Received		0.0415																								3-month LIBOR
Interest Rate Paid		3-month LIBOR + 1.96%																								0.0290
Hedge Maturity Date		May 01, 2014																								Dec. 01, 2022
Fair Value Gain (Loss) March 31, 2012	4	14																								(10)
Total deferred gains and losses are expected to be amortized into earnings
Estimated Gain (Loss) to be Reclassified for the 12 Months Ending March 31, 2013	(16)		1	(3)	(1)	(1)						(11)
Total Deferred Gains (Losses) Amortized Through	2037		2035	2037	2020	2022	2022					2016
Notional amount of outstanding foreign currency derivatives
Notional Amount							24.9		18.1		6.8
Forward Rate								1.3209		1.3805
Hedge Maturity Date										Various through March 2014	Various through March 2014
Fair Value Gain (Loss) March 31, 2012